BACKGROUND An aptamer based biosensor (aptasensor) was developed and evaluated for rapid colorimetric detection of Escherichia coli (E. coli) O157:H7. METHODOLOGY/PRINCIPAL FINDINGS The aptasensor was assembled by modifying the truncated lipopolysaccharides (LPS)-binding aptamer on the surface of nanoscale polydiacetylene (PDA) vesicle using peptide bonding between the carboxyl group of the v...

We present a novel reflectance-based colorimetric aptasensor using gold nanoparticles for the detection of oxytetracycline for the first time. It was found that the reflectance-based measurement at two wavelengths (650 and 520 nm) can generate more stable and sensitive signals than absorbance-based sensors to determine the aggregation of AuNPs, even at high AuNP concentrations. One of the most ...

We developed a facile one-step approach to synthesize DNA-templated Ag/Pt bimetallic nanoclusters (DNA-Ag/Pt NCs), which possess highly-efficient peroxidase-like catalytic activity. With this finding, an aptamer based sandwich-type strategy is employed to design a label-free colorimetric aptasensor for the protein detection with high sensitivity and selectivity.

Colorimetric aptasensors using unmodified gold nanoparticles (AuNPs) have attracted much attention because of their low cost, simplicity, and practicality, and they have been developed for various targets in the past several years. However, previous research has focused on developing single-target assays. Here, we report the development of a homogeneous multiplex aptasensor by using more than o...

Gold nanoparticle (AuNP) based colorimetric aptasensor have been developed for many analytes recently largely because of the ease of detection, high sensitivity, and potential for high-throughput analysis. Most of the target aptamers for detection have short sequences. However, the approach shows poor performance in terms of detection sensitivity for most of the long-sequence aptamers. To addre...

A novel strategy for the fabrication of a colorimetric aptasensor using label free gold nanoparticles (AuNPs) is proposed in this work, and the strategy has been employed for the assay of adenosine deaminase (ADA) activity. The aptasensor consists of adenosine (AD) aptamer, AD and AuNPs. The design of the biosensor takes advantage of the special optical properties of AuNPs and the interaction b...

In this work, a simple gold nanoparticles (AuNPs) based colorimetric biosensor was developed for chlorpyrifos (Chl) detection using an aptamer as the capture probe. The Chl-aptamer with low dissociation constant (Kd) of 58.59 ± 6.08 nmol/L selected by ssDNA library immobilized systematic evolution ligands enrichment (SELEX). absence Chl, acted stabilizer AuNPs in salt solution. presence highly ...

Sensitive monitoring of the target products during biosynthesis process is crucial, and facile analytical approaches are urgently needed. Herein, phosphatidylserine (PS) was chosen as model target, a colorimetric aptasensor developed for rapid quantitation in samples. A chimeric aptamer constructed with two homogeneous original PS aptamers. Specific recognition between results desorption from s...

The development of simple and low-cost approaches to the detection of immunoglobulin E (IgE) would provide a method for the early diagnosis and prevention of atopic diseases. The current methods of detection are generally tedious, multi-step processes and are limited by the high cost of the labeled proteins. We describe here a label-free structure-switching colorimetric method for the simple me...